LONDON — It is likely that there are now more British Muslims fighting for the Islamic State than for Britain's military.

Britain's Ministry of Defense confirmed to USA TODAY that there are approximately 600 British Muslim servicemembers in its armed forces of almost 200,000 people. Official government estimates put the number of British Islamic State fighters operating in Syria and Iraq at up to 800. The Foreign Office cautioned Thursday that it is difficult to provide precise numbers.

The militant who beheaded American journalist James Foley in a horrifying video released this week spoke with a British accent. United Kingdom Foreign Secretary Philip Hammond acknowledged that the militant in the video could be a British national. And he knows the problem of British jihadists is not a new one.

"This is something we have been tracking and dealing with for many, many months and I don't think this video changes anything," he said. "It just heightens awareness of a situation which is very grave."

Khalid Mahmood, a member of Parliament from an area with a high proportion of Muslim residents, said government estimates of the number of British Islamic State fighters currently in the Mideast is far too conservative. He told Newsweek magazine this week that at least 1,500 extremists are likely to have been recruited to fight in Iraq and Syria over the last three years.

"There are an unacceptable number of Britons fighting for jihadist forces," he said.

Experts say the number of Americans fighting for the Islamic State is much lower. Joseph Young, a criminology professor at American University and expert on political violence, said simple geography and the complex cultural differences between the U.S. and Europe are primary reasons why.

Young, who said common estimates put the number of American fighters for IS at 100 to 150, said just getting to Syria or Iraq is extremely complicated from North America. However, the Islamic State's home region is practically next door for Europeans.

"We also do a better job of integrating our minority communities," Young said. "Isolation of minority groups is a much bigger problem in Europe."

Raffaello Pantucci, a researcher at Royal United Services Institute in London, said many young men facing poor job prospects in the U.K. find the IS narrative of defending Islam hard to resist. He agrees with Young -- Syria and Iraq are relatively accessible from England.

"These people can go look online and just decide to participate," he said. "With its proximity to Europe it's just so easy to do."

Ghaffar Hussain, of the Quilliam Foundation, a counter-extremism think tank in Britain, said the lure could be empowerment for many British Muslims with grievances over their treatment in a predominantly non-Muslim society.

"It makes them feel like they are part of something that is important to the world," he said. "If you feel like you don't really fit in or if Muslims are being attacked and a narrative comes along that explains all that away in a simple way, that is attractive."

Hussain said a task force was set up – called Channel – to identify people who have been flagged in schools and institutions as being at risk of being drawn into extremism. Channel then pairs them with a mentor who assesses their needs and tries to offer support. But, he said, a major failing of the program is that it only works if individuals are flagged by the system.

"When it comes to the hard-edge, counterterrorism stuff, a lot of good work has been done by the government in terms of thwarting a hell of a lot of plots in recent years, but there are a lot of gaps outside of Channel," Hussain said. "Taking it seriously is one thing, knowing what to do is another."

Hussain said that extremism of the kind that is leading British nationals to Iraq and Syria is not limited to Britain but is a western European phenomenon seen in Holland, France, Denmark and other places. He said would-be fighters probably enter Syria through Turkey, though it's not exactly clear how.

Christopher Davidson, a Mideast expert at Durham University, said there's been a massive lack of attention to the flow of Westerners headed to the region. "As long as they have been supposedly fighting the (Syrian President Bashar) Assad regime, authorities have turned a blind eye to it. Now that they are going to Iraq we are starting to experience the blow back," he said.

Young noted that completely stopping the flow of Westerners is probably asking too much.

"Young men throughout time and space have done these kinds of things," he said.

Buttons in support of James Foley are displayed during a panel discussion about the importance and dangers of reporting on world conflicts at a Free James Foley event in Boston. Don Emmert, AFP/Getty Images

John, center, and Diane Foley, left, parents of James Foley, listen to a panel discussion about the importance and dangers of reporting on world conflicts at a Free James Foley event in Boston in 2013. Don Emmert, AFP/Getty Images

Freed journalists Nigel Chandler, left, of Britain, Manu Brabo of Spain, James Foley of the U.S. and his compatriot Clare Morgana Gillis, right, arrive at Rixos Hotel in Tripoli, Libya, on May 18, 2011, following their release. They had disappeared April 4 while covering the conflict in Libya. Mahmud Turkia, AFP/Getty Images

John Foley, left, and his wife Diane, back to camera, talk with supporters July 25, 2013, in Rochester, N.H. after a moment of silence for James Foley, their missing son. Foley, 39, was last seen Nov. 22, 2012, in northwest Syria. Jim Cole, AP